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<head>
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    <title>Document</title>
    <script>
        function unique(arr) {
            var newArr = [];
            //遍历旧数组,拿旧数组中的元素和新数组进行比较,如果新数组中没有该元素就存到新数组中
            for (var i = 0; i < arr.length; i++) {
                if (newArr.indexOf(arr[i]) === -1) {
                    newArr.push(arr[i]);
                }
            }
            return newArr;
        }
        var arr = ['c', 'a', 'z', 'a', 'x', 'a', 'x', 'c', 'b'];
        var demo = unique(arr);
        console.log(demo);
    </script>
</head>

<body>

</body>

</html>